Quick Answer
The answer is to enable session sync on the HA2 link. This is correct because session sync continuously replicates the active firewall’s session table to the standby firewall over the dedicated HA2 interface, ensuring that when a failover occurs, the new active firewall already has a populated session table and can maintain existing connections without interruption. Without this configuration, the standby firewall starts with an empty session table, causing all TCP and UDP sessions to be dropped immediately upon failover. On the PCNSE exam, this question tests your understanding of high availability session preservation, a common trap being that candidates mistakenly focus on HA1 (management sync) or HA3 (data path), which do not handle session state replication. The key memory tip is: HA2 is for the session table, HA1 is for the config—think “2 for the table, 1 for the file.”
This PCNSE practice question tests your understanding of managing troubleshooting and high availability. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
During an HA failover, the new active firewall's session table is empty, causing all existing connections to be dropped. Which configuration change would prevent this?
Configure HA3 for stateful inspection.
Why wrong: HA3 is for session ownership, not synchronization.
Increase HA1 keepalive timer.
Why wrong: This affects failover detection, not session preservation.
Enable config sync on HA1.
Why wrong: Config sync synchronizes configuration, not sessions.
Enable session sync on HA2.
Session sync ensures sessions are replicated to the passive firewall.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Enable session sync on HA2.
Option D is correct because enabling session sync on the HA2 link ensures that session state information is continuously replicated from the active firewall to the standby firewall. During a failover, the new active firewall already has the session table populated, so existing connections are preserved and not dropped. Without session sync, the standby firewall starts with an empty session table, causing all existing TCP/UDP sessions to be torn down.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Configure HA3 for stateful inspection.
Why it's wrong here
HA3 is for session ownership, not synchronization.
Increase HA1 keepalive timer.
Why it's wrong here
This affects failover detection, not session preservation.
Enable config sync on HA1.
Why it's wrong here
Config sync synchronizes configuration, not sessions.
Enable session sync on HA2.
Why this is correct
Session sync ensures sessions are replicated to the passive firewall.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is confusing configuration synchronization (config sync) with session state synchronization (session sync), leading candidates to incorrectly select config sync on HA1 as the solution for preserving active connections during failover.
Detailed technical explanation
Session sync uses the dedicated HA2 link (or HA2 backup) to replicate session entries from the active firewall to the standby firewall in real time. The synchronization includes Layer 4 state, NAT translations, and application-level state for protocols like TCP, UDP, and ICMP. In a real-world scenario, without session sync, a failover during a large file transfer or VoIP call would drop the connection, requiring the client to re-establish the session, which can cause application timeouts and user disruption.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the PCNSE exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Managing Troubleshooting and High Availability — study guide chapter
Learn the concepts, then practise the questions
Managing Troubleshooting and High Availability practice questions
Targeted practice on this topic area only
All PCNSE questions
516 questions across all exam domains
Palo Alto Networks Certified Network Security Engineer PCNSE study guide
Full concept coverage aligned to exam objectives
PCNSE practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise PCNSE questions linked to Manage, Monitor and Operate.
Practise PCNSE questions linked to Securing Traffic and App-ID.
Practise PCNSE questions linked to Securing Users and Applications with Authentication.
Practise PCNSE questions linked to Decryption and SSL Inspection.
Practise PCNSE questions linked to Managing Troubleshooting and High Availability.
Practise PCNSE questions linked to Deploy and Configure Firewalls.
Practise PCNSE questions linked to Core Concepts and Architecture.
Practise PCNSE questions linked to Secure Access and VPN.
Practise PCNSE questions linked to Troubleshoot.
Practise PCNSE questions linked to PCNSE fundamentals.
Practise PCNSE questions linked to PCNSE scenario.
Practise PCNSE questions linked to PCNSE troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Managing Troubleshooting and High Availability — This question tests Managing Troubleshooting and High Availability — Read the scenario before looking for a memorised answer..
The correct answer is: Enable session sync on HA2. — Option D is correct because enabling session sync on the HA2 link ensures that session state information is continuously replicated from the active firewall to the standby firewall. During a failover, the new active firewall already has the session table populated, so existing connections are preserved and not dropped. Without session sync, the standby firewall starts with an empty session table, causing all existing TCP/UDP sessions to be torn down.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 11, 2026
This PCNSE practice question is part of Courseiva's free Palo Alto Networks certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCNSE exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.